大象传媒

Weighing less than 30 grams, a tiny television camera is like a lens on a microchip and can be harmlessly placed on tame birds to allow us a view of their all important tools of the trade: wings and tail. Three birds, three designs and all specialists in their field. First, the golden eagle - the ultimate soarer. As she floats on the updraught of mountain winds her wings flex, bending in the middle. At the tips, primary feathers spread like fingers feeling for the tiniest current and giving maximum lift for minimal effort. The reason birds find it so easy to fly is because they have so much movement in their wings, unlike a rigid winged aircraft. An aeroplane wing uses flaps of metal to crudely move the air, whereas a bird wing constantly flexes and twists to give much more subtle control. With infinitely adjustable wings, an eagle can stay soaring for hours on end. The tail is also constantly twitching, working with the wings to fine tune flight even further. For that extra bit of lift, the fan sometimes fans right out to join the wings and make one big delta wing. Drawn back in, the tail gives that extra burst of speed for the kill. This all gives a stable platform for its eyes. Despite the ever-changing buffeting wind, an eagle can spot a mountain hare at two miles with telescopic vision. With the help of on-bird cameras, NASA is now designing the planes of the future to be just as flexible. Next is the fastest animal on the planet, the peregrine falcon. Wings that are stretched to gain height one moment, are tucked away the next as the peregrine flips round in a stoop. It nosedives at 150mph then, seconds before impact, it opens its wings to pull a brain-numbing bottom turn that would cause a human to black out. The second time round, a split-second barrel roll keeps her target in vision without the need to turn her head. At this speed, even a head turn would send her wildly out of control. Next is the goshawk, the master of manoeuverability, flying through woodland. It feels for the air like an eagle, swings its wings like a falcon, but is just inches from the ground and a breath away from colliding with a tree. Split-second timing allows her to slip through the tiniest gap in the trees. Scientists examining images of a goshawk flying have concluded that no existing aircraft comes anywhere close.